He looked like that at the moment of doing it because he just got done warping Deidara's arm. There's no difference in his appearance from panel 1 to 2 other than him squinting trying to aim the kamui better. You didn't disprove a single thing I said...
Look closely. Besides panting, which wasn't present at the panel before it, Kakashi's veins in his eye are even more exposed than they were before. This pretty much tells us that Kakashi indeed exhausts himself from using Kamui, no matter whether he makes a hit or not.
Naruto developed an S-ranked technique, which is something he lacked, and on top of doing that, use the shadow clone method of training which allowed him to train insanely faster than really anyone else in the series is capable of. And it wasn't simply due to the rasenshuriken, either. Naruto's tactical intelligence improved as well. I'd argue that Kakashi still > Naruto at that point, but Naruto definitely closed the gap with developing that technique and using that training method.
Kakashi's "power up" would be him now being capable of warping an entire human body instantly with kamui. No one has improved their chakra reserves this drastically in the entire history of this manga, and I know no one has EVER done it without the use of training. You've given no explanation for it. There are several hints that Kakashi was running out of chakra prior to the cloak. It was him saying what he did when creating the clone, then the TBB incident where Gai stated he didn't have enough power to warp the TBB's away(and Kakashi didn't object that statement).
No one has EVER awakened MS while being non-uchiha, either.
I won't repeat myself for the third time regarding his chakra worries.
As of Guy's statement, he clearly meant that Kakashi would need to kamui all five bijuudamas one after another in a very short period, several second at max. Kakashi was shown to be able to use Kamui instantly, but he never was shown using it continuously one after another. In other words, that statement was not about chakra, but Kakashi's Kamui prowess in general.
You continually fail to grasp logic. You can make up all your ridiculous formulas for chakra usage, but there is no explanation for Kakashi having this much chakra.
There is explanation. Kishi's will. He might do whatever the heck he wants. It wasn't stated that one cannot increase his chakra reserves so much during a short period time, so if Kishi wanted Kakashi to suddenly increase in stamina - he could do it. Kakashi's a genius and it's not the first time he presents something everyone would think to be very difficult (creating a powerful A-rank lightning technique at the age of 13) or even impossible (a non-uchiha awakening Mangekyo).
You say that "I can make up my ridiculous formulas for chakra usage" clearly meaning that you find mathematical analysis stupid or pointless, to say the least. And you still are here, arguing with me even though I clearly stated at the beginning - don't like this form of analysis - don't read it. You don't read it - don't reply.
I think that, after all, it's someone else that has problems grasping logic.
That's what I get for arguing with someone who initially thought Kakashi would faint after using two kamuis, hmm.
Edit:
I'm going to sleep now, so listen carefuly.
You have your opinion (his chakra was restored) and I have mine (his chakra reserves increased). As of now I assume my version the default one while you seem to see yours as default. Default meaning the one used until official explanation is given.
Do you know what's the difference between us, then? The difference is critical thinking.
I don't agree with your theory, but I take it into account as a thing that might affect the reliablity of my calculation.
Look, whole part 3 of the thread is devoted to finding arguments to show that my own analysis doesn't work.
That's what we call critical thinking. Looking at both sides of a coin. That's what you lack. You don't even consider the possiblity of me being right. You started to tell me I don't use logic long before the post I'm replying to. You did it even after I presented a rebuttal. I guess my nerves had their limits, too, as in this very post I also started to say you don't grasp logic. Now, from time perspective, I'm aware of that.
If you're thinking of an argument, you should immediately think of a rebuttal to that. If you don't find any rebuttal, find an unrelated argument against. That's the way of being as unbiased as possible. I don't always manage to do that, because it's not so easy, but I think I was successful in this thread.
Yeah, and that would be all from me. See you around.